The present invention relates to a multiaxial, multilayer fabric suitable for being used for ballistic uses, and to a process for manufacturing that fabric.
Several types of fabrics are known and are used for manufacturing bulletproof jackets or similar articles of manufacture, which are presently used for ballistic uses.
They can be grouped, for the sake of simplicity, in three categories namely:
1. fabrics manufactured according to a typical weft/warp arrangement, which are simply sewn or coupled to a common matrix; PA1 2. fabrics manufactured as the fabrics from category 1., further, comprising plastic films, nonwovens and/or impregnating resins, as reinforcer elements and; PA1 3. fibrous fabrics with two monoaxial layers mutually superimposed with their fiber directions perpendicular to each other, which are coated on their outermost surfaces with plastic resins or films in order to supply the structure with mechanical strength, and simultaneously, flexibility.
The first type of fabrics is manufactured by means of a by now well mature technology and, owing to this reason, can be manufactured with rather low manufacturing costs.
Furthermore, the ballistic panels manufactured from this type of fabric secure good drapeability and a rather good comfort, because the layers which compose them are mutually bonded by sewing stitches.
The ballistic strength of this type of fabric against bullets is acceptable, but the levels of trauma suffered by the struck regions of wearer's body are very high.
In order to reduce such degree of trauma, more layers of thread must be used, with the consequent result that the weight of the manufactured article considerably increases.
Furthermore, the garments so produced display reduced drapeability and are less comfortable during wearer's movements.
However, this first type of fabric is the most widely used, at present, for ballistic uses of general character.
The resin-treated traditional fabrics display a somewhat higher ballistic strength than the above referenced category 1 fabrics and substantially a rather good flexibility, but suffer from other drawbacks, such as low comfort of use (because their weight is higher), and high production costs.
In order to increase the level of ballistic strength, rigid or semirigid panels are furthermore manufactured which, unfortunately, display negative characteristics from drapeability and comfort viewpoints.
In order to try to overcome the above-mentioned drawbacks without giving up the advantages offered by the above-described structure, the use was furthermore proposed of a biaxial, two-layer fabric made from aramidic or polyethylene materials or the like, coated with flexible resins on the outer surfaces of the layers.
This type of fabric shows a good ballistic strength, however relatively high values of trauma of hit parts of wearer's body are observed. The drapeability is acceptable.
Unfortunately, the manufacturing cycle for this product is particularly complex, because it is carried out batchwise. Furthermore, the threads are arranged perpendicular to each other and that angle cannot be varied.
Furthermore, this type of processing does not allow the manufacturer to mutually superimpose more than two successive thread layers because, when the fabric is bent to fit to the wearer's body, it generates creases which tend to separate the threads from the matrix. Furthermore, the manufacturing costs of a garment manufactured from such a kind of fabric are very high.